Numerical Analysis of the Design of a Subsea Gas Pipe Route Passing the Thrust Fault Using the Finite Element Method

Abstract

In submarine pipeline route planning, there is a possibility that the pipeline route will pass through a potential geohazard in the form of an active subduction zone. The planned pipeline route in this study is located in the Arafura Sea, which cross path through a subduction zone system that has a thrust fault mechanism. To analyse the structural response of the pipe passing through the thrust fault, a numerical analysis using the finite element method is being used. Numerical modelling will accommodate the interaction of nonlinear behaviour between an API 5L X70 steel pipe and a cohesive clay soil. Then the pipe section in the fault area will be examined in detail with a parametric study of the variation in the angle of the pipe passing through the fault line and the impact of various earthquake magnitudes. The results of the numerical analysis show that the maximum von mises stress and maximum strain values will have a greater value for a larger pipe angle and a greater earthquake magnitude. The axial strain along the pipe will be significantly increased at the fault line and has a greater value for the pipe on the hanging wall than the pipe on the footwall. It can be concluded that the optimum route for the submarine pipeline passing through the thrust fault should be kept as small/short as possible against the fault line. The results of this analysis are expected to provide an overview of the behaviour of submarine pipes that pass through the thrust fault so that the pipe route designed can be optimal by considering safety, integrity, and efficiency.